Brushes used for cleaning floors have been generally known for many years. The brush art has progressed from manually operated brushes, limited by human endurance, to machine driven brush units that are capable of cleaning large floor areas in a short time with a minimum amount of human effort. The rotary brush units described hereinafter comprise one type of machine unit. In general, these machines employ a generally flat disk which is supported above the floor surface by stiff brush fibers or the like. A circular pad of scrubbing or polishing material such as synthetic fibers, steel wool or the like are engaged and held by the brush fibers and rotate therewith. It is this pad which engages the floor and carries cleaning compounds and does the actual work on the floor surface. The center of the disk is secured to the generally vertical shaft of a power unit such as an electric motor and the housing of the power unit has a handle extending upwardly and outwardly from the disk axis. An operator uses the handle to control the unit and by tipping the unit, he can cause it to move across the floor, to the left or right, or forward or backward.
Within the last few years, the floor cleaning industry has developed new high-speed rotary floor cleaning machines. These new high-speed machines operate in a range near 300 revolutions per minute whereas earlier floor cleaning machines operate in a range near 175 revolutions per minute. With the advent of the new high-speed machines, a number of new problems have arisen relating to the structure and durability of the brushes. It has been found that the brushes used on the earlier machines are not suitable, nor are they safe for use on the new high-speed machines. Because the new machines operate at such high speeds, a tremendous amount of torque is generated, particularly in starting up the machine and when the brush encounters localized resistance especially under only a portion of the disk. Should the direction of the torque due to the driving force be altered upon encountering resistance, the results could be disasterous. For example, if the brush driven at high speed encounters a rough floor or a particularly sticky substance on the floor, the balanced torque is transformed into a violent moment where the moment arm is the distance from the center of the power unit to the point where the resistance is encountered. This moment produces a vibration of the entire machine, rapid acceleration of the machine across the floor or the brush itself breaks down hurling bits and pieces helter-skelter. Thus, the operator of the machine and anyone or anything in the vicinity is imperiled. Furthermore, lesser resistance causes a chatter of the working brush surface producing unsatisfactory polishing or cleaning. Similarly small discontinuities in the floor surface will produce brush chatter and render the machine hard to control. Such chatter will also reduce the quality of the work done by the machine.
To avoid the dangerous possibilities and optimize the quality of the work, it has been found that the brushes used on the high-speed machines must be more durable and must reduce the vibration transferred to the machine. Basically, vibration under a uniform balanced load is reduced by delicately spin balancing the brush. By incorporating some type of shock absorbing means into the brush, the vibration resulting from load changes can also be reduced. One shock absorbing means presently used for brushes designed to operate on high-speed machines employs plastic spines extending downwardly from an integral flexible plastic back supported by a polyurethane foam disk on a rigid disk of equal diameter such as 24 inches. The high-speed machine rotates the sandwich of rigid disk, foam disk flexible support, spines and any polishing fabric below the spines and carried thereby very near the floor so that the sandwich should be compressed to absorb the shocks caused by the torque directional changes occurring when brush resistance or floor irregularities are encountered.
Although the sandwich construction described above has resulted in some improvement, new problems have arisen that heretofore have remained unsolved. For example, because the entire sandwich including the polyurethane foam disk is positioned so near the floor when the floor cleaning machine is in operation, the foam disk frequently contacts the cleaning solutions and other obstacles on the floor that cause a deterioration of the foam or a tearing away of portions of the foam disk. These destructions of the foam disk upset the delicate spinning balance needed with this type of brush, as well as significantly reducing its shock absorbing capabilities. In addition, since the entire sandwich including the foam disk has the full diameter of the brush and the foam disk must be thick enough to absorb most shocks, the diameter of the brush surface must be substantially less than the diameter of the machine's bell housing which covers the rotating brush. This precaution avoids contact between the brush and bell housing. Thus, the machine is unable to clean the floor closely adjacent to the walls and the machine is generally less efficient. Furthermore, the use of the large foam disk is costly, creates construction problems, requires extremely careful bonding and lowers responsiveness and power transmitting capabilities. The present invention solves the problems that have been found in the prior art and provides a shock absorbing brush with a rigid brush construction to operate safely on high-speed floor cleaning machines. It is an object of the present invention to provide a floor cleaning brush that has a unique shock absorbing and power transmission means removed from a position where it contacts cleaning solutions or obstacles on the floor.
Another object of the present invention is to increase the cleaning efficiency of high-speed machine driven brushes by providing a rigid brush mounted on a shock absorbing means which provides positive reliable power transmission.
Another object of the present invention is to provide an improved brush construction providing optimum torque transmission characteristics with controllable or adjustable shock absorption.
A further object of the present invention is to provide a brush that is safe to use at high revolving speeds by providing a construction that reduces the torque stress on the machine and brush and thereby reduces machine maintenance and machine vibration.
Still another object of the present invention is to provide a more durable brush that is less expensive to construct than the presently used brushes.
A further object of the present invention is to provide a brush that cleans the floor area within a minimum distance from the walls.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and appending claims, and upon reference to the accompanying drawings.